Modern Mining March 2018

DIAMOND MINING

243 individual samples for treatment. The LDD programme was contracted to De Wet Drilling, which used its Elephant drill rig. This rig has a direct hydraulic pullback of 120 tonnes and a rotational torque of 100 000 Nm. Tsodilo’s DMS plant was purchased in March 2015 by Tsodilo’s subsidiary, Newdico, from the original owner, De Beers Botswana Prospecting Ltd. The plant was built for De Beers in Kimberley, South Africa, and later transported and installed just outside Letlhakane to evaluate the AK6 kimberlite (now the Karowe mine). It was used over several years for the feasibility study of AK6. The plant has been exten-

sively refurbished by Tsodilo and was commissioned in January this year using the historic tailings material to test the plant. The facility consists of a scrubbing unit, jaw and cone crushers, screening units, a DMS cyclone and a DMS concentrate cage to collect and secure the DMS concentrate. To date (13 March), 724,7 tons have been processed through the plant representing 141 samples out of a total of 243 or 61 % of the tonnage. These 141 samples have generated 2 778,6 kg of concentrate translating to a DMS yield of 0,38 %. Tsodilo anticipates that the treatment of the LDD samples through the DMS plant will be completed in the first week of April. The treat- ment of the tailings material of BK16 will then resume. The second consignment of 71 drums of con- centrate has been securely moved to Tsodilo’s final recovery area at its secure complex in Maun, where it installed a Polus-M X-ray sorter from Bourevestnik, Inc in January this year. Numerous diamonds were recovered during the setup, calibration and instruction period. The sorter has been set up to treat dry DMS concentrate in the size range of -8 +3 mm and -3 +1 mm. To date, it has treated 32 LDD samples and produced cumulatively 7,0 kg of concen- trate in the 1 to 3 mm size range and 0,6 kg of the 3 to 8 mm size material. The material in the 8 to 12 mm size range for these 32 LDD samples has a combined weight of 43,6 kg. The X-ray sorted concentrates will be hand

sorted in the Maun secure sorting facility by a third-party sorter. The -12 +8 mm material will also be hand-sorted in Maun. The recovered diamonds will be transported to the Diamond Technology Park in Gaborone for acid cleaning and valuation. The company is exploring ave- nues to obtain the use of a larger Bourevestnik machine to treat the plus 8 mm fraction. The sorter operation concept is based on the use of diamonds’ property of luminescence under X-ray impact and on the difference of those properties with diamonds and associate luminescent minerals. Photos courtesy of Tsodilo Resources

Another view of the DMS plant. It consists of a scrub- bing unit, jaw and cone crushers, screening units, a DMS cyclone and a DMS concentrate cage.

The Polus-M X-ray sorter at Tsodilo’s secure facility in Maun.

feature

March 2018  MODERN MINING  41